We emphasize again that, compared to [1]}, the Stage 2 TSRBLOD ROM is not only
independent from \(\mathcal {T}_h\) , but also from the number of coarse elements. Its size only depends
on the number of selected basis vectors in sec:stage2basgen.
Further, in contrast to [1]}, the derived error estimator fully takes the effect of the errors of
the reduced corrector problems on the resulting global solution into account and, thus,
rigorously bounds the error of the ROM w.r.t. the LOD solution.
